Mitral Stenosis

BASICS

Description

• Narrowing of mitral valve area obstructing LV inflow → ↑LA pressure → pulmonary HTN
• Normal valve area: 4–6 cm²; symptoms appear when <2.5 cm²

Disease Staging: - Stage A: At risk (no obstruction/symptoms) - Stage B: Progressive MS (MVA >1.5 cm², no symptoms) - Stage C: Asymptomatic severe MS (MVA <1.5 cm²) - Stage D: Symptomatic severe MS with ↓exercise tolerance

EPIDEMIOLOGY

• RHD: 40.5 million globally, 305,000 deaths/year
• U.S. incidence of ARF: <2/100,000 children

ETIOLOGY & PATHOPHYSIOLOGY

• Most common cause: Rheumatic heart disease (RHD)
• Path: leaflet thickening, commissural fusion, “fish mouth”
• Chronic ↑LA pressure → AF, pulmonary HTN, right HF

Other causes: - Calcification, congenital MS, SLE, Whipple, carcinoid, MDMA, methysergide

RISK FACTORS

• ARF, low SES, recurrent GAS infections
• Aging, chest radiation, drugs (MDMA, ergot alkaloids)

PREVENTION

• Prompt GAS treatment, ARF prevention (Jones criteria)
• TTE screening in high-prevalence areas

ASSOCIATED CONDITIONS

• Atrial fibrillation, aortic/tricuspid valve disease, pulmonary HTN, embolic events, endocarditis

DIAGNOSIS

History

• Latency: 10–40 yrs post-ARF
• Symptoms: dyspnea, chest pain, AF, hemoptysis, PND, orthopnea
• Advanced disease: JVD, hepatomegaly, ascites, edema
• Mitral facies during pregnancy

Physical Exam

• JVD, diastolic thrill, RV lift
• Classic murmur:
• Loud S1, OS, diastolic rumble with presystolic accentuation
• Best at apex in left lateral decubitus
• Murmur increases with exercise, short S2-OS interval (<70ms) = severe MS
• If pulmonary HTN: loud P2, Graham Steell murmur

Initial Tests

• ECG: LA enlargement, AF, RVH
• CXR: LA enlargement, double density, Kerley B lines
• TTE: initial and follow-up test of choice
• TEE: prior to PMBC/PMBV or if thrombus suspected

Advanced Testing

• Exercise Doppler echo: symptom-discrepancy
• Cardiac cath: if echo inconclusive or discrepancies
• CT: evaluate MVA, LA size, CAD

Interpretation

• MS severity (MVA):
• Normal: 4–6 cm²
• Progressive: >1.5 cm²
• Severe: <1.5 cm²
• Very severe: <1.0 cm²

TREATMENT

General Measures

• Symptom-based treatment
• Medical management if MVA >1.5 cm² + asymptomatic

Medications

• Anticoagulation:
• Warfarin if: MS + AF, prior embolism, or LA thrombus
• DOACs not approved for moderate/severe MS with AF
• Antibiotic prophylaxis for RHD recurrence
• Diuretics: for pulmonary congestion
• β-blockers, non-DHP CCBs, or ivabradine for rate control
• Consider cardioversion in new AF <6 months

Second Line: - Amiodarone, digitalis: for refractory AF or LV dysfunction

Surgical/Procedural Options

• Candidates for intervention:
• Severe MS (MVA <1.5 cm²) with symptoms or AF
• PMBC/PMBV if favorable valve morphology
• Not candidates:

• MVA >1.5 cm², LA thrombus, significant MR, valve calcification, moderate TR/TS, CAD needing CABG

• Surgical Options:

• PMBC, open or closed commissurotomy, MVR
• Consider valve type based on age, bleeding risk

Pregnancy

• Prepregnancy cardiology consult for known MS
• Warfarin safe in 2nd/3rd trimester; UFH near delivery

ONGOING CARE

Follow-Up

• Very severe MS (MVA <1 cm²): yearly echo
• Severe MS (MVA ≤1.5 cm²): echo q1–2 years
• Mild/moderate MS (MVA >1.5 cm²): echo q3–5 years
• Monitor for AF, rapid symptom progression

Diet

• Salt restriction if pulmonary congestion

PROGNOSIS

• Latent period after ARF: 10–30 years
• 10-year survival:
• Asymptomatic: ~80%
• Debilitating symptoms: 0–15%
• If pulmonary HTN present: mean survival <3 years
• Commissurotomy helps but restenosis may recur

COMPLICATIONS

• AF, systemic embolism, right/left HF
• Pulmonary HTN, hepatic congestion
• Endocarditis

ICD-10

• I01.1: Acute rheumatic endocarditis
• Q23.2: Congenital mitral stenosis
• I34.2: Nonrheumatic mitral stenosis

Clinical Pearls

• Asymptomatic → follow yearly exam + periodic echo
• Once symptoms start → initiate medical therapy
• Almost all MS progresses → surgery often required eventually